[NTG-context] Strange backgroundcolors with showgrid and luacode

[Otared Kavian]

Dear all,

When typesetting an old list of exercises, I noticed that when \showgrid is active and a luafunction is called, there is some unwanted and strange background colors (gray and blue, or yellow and blue). Thes background colors seems to show up on an unfilled page when a lua function is used, and I could come up with the following minimal example which gives the attached PDF.

Could someone, please, tell me what I am doing wrong?

Best regards: OK

%%%% begin test-strange.tex

 \showgrid
%\setuplayout[grid=yes]

\startluacode
AdditionTest = function(nn)
	local a = {}
	local b = {}
	for i = 1,nn do
		a[i] = i 
		b[i] = nn - i 
	end
	context.midaligned("\\bfa Exercises")
	context.blank()
	context.startcolumns { n = 3 }
	context.starttabulate { "|r|c|r|c|r|" }
	for i=1,nn do
		context.NC()
			context(a[i])
		context.NC()
			context.mathematics("*")
		context.NC()
			context(b[i])
		context.NC()
			context("=")
		context.NR()
	end
	context.stoptabulate()
	context.stopcolumns()
	context.page()
end
\stopluacode

\starttext
\ctxlua{AdditionTest(12)} % the background colors, gray and blue, show up when a lua function is called

% \ctxlua{AdditionTest(120)} % the background colors, yellow and blue, show up when a lua function is called

% \input knuth % the background colors do not show up here

\stoptext
%%%% end test-strange.tex

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